The present invention relates to composite yarns useful in the manufacture of protective garments, such as cut and puncture resistant glove liners to be worn by doctors, dentists, nurses and other healthcare personnel beneath latex gloves.
Latex gloves are commonly worn by healthcare personnel as barrier protection against diseases carried by a patient's blood and other body fluids. Use of this protection has become particularly critical with the advent of AIDS.
Unfortunately, latex gloves do not provide any protection against cuts or needle punctures which occasionally occur. These cuts and punctures are especially hazardous during surgery, since body fluids can enter the glove and the user's body through the cut or puncture created.
To address this problem, it has been suggested that medical personnel should wear cut-resistant safety gloves beneath the latex gloves. Safety gloves, which were originally designed to be worn by meat cutters, sheet metal workers, and the like, have proven to be unsuitable for use by healthcare personnel, however, since they are bulky, eliminate tactile sensation, and impede delicate manipulations required by healthcare personnel in the performance of their duties.
Examples of patents describing safety gloves exhibiting cut-resistant characteristics, and composite yarns used in the manufacture of such gloves, include U.S. Pat. No. 4,384,449 to Byrnes et al, which describes gloves manufactured from a composite yarn having a first core strand of wire which preferably has a diameter of from about 0.004 inch to about 0.006 inch, a second core strand of an aramid, and two covering strands of an aramid. The aramid strands have deniers of from about 200 to about 1500, preferably 200 to 400.
U.S. Pat. No. 4,470,251 to Bettcher describes safety gloves manufactured with a similar composite yarn; namely, a yarn having two core strands of annealed stainless steel wire, one core strand of an aramid, one covering strand of an aramid and one covering strand of nylon. The steel wire has a diameter of from 0.002 to 0.006 inch, and the aramid strand has a denier of from 500 to 1100 in the core strand and 400 in the covering strand.
Safety gloves are also described in U.S. Pat. Nos. 4,777,789 and 4,838,017 to Kolmes et al. The gloves described in these patents are prepared using a composite yarn having one or more core strands of an extended-chain polyethylene such as Spectra, manufactured by Allied-Signal, Inc., a core strand of wire having a diameter of 0.003 to 0.006 inch, and one or more covering strands of Spectra, nylon or other fiber which has a denier of 200 to 1500.
Gloves described in U.S. Pat. No. 4,936,085 to Kolmes et al, are manufactured with a composite yarn having at least one core strand of fiberglass, and at least two covering strands, one of which is fiberglass. The fiberglass has a denier in the range of from about 185 to about 2000, with a range of 375 to 1000 being preferred for the core and a range of 500 to 1000 being preferred for the covering. The preferred total denier of the yarn is in the range of about 3000 to about 6000.
U.S. Pat. No. 5,177,948 to Kolmes et al, which is a continuation-in-part of the application leading to U.S. Pat. No. 4,936,085, further discloses that the non-fiberglass fibers may include Spectra or an aramid.
In addition to conventional safety gloves of the type described in the aforesaid patents, surgical glove liners have also been knitted using 100% Spectra fibers. There is still a need, however, for an even lighter, smaller composite yarn strand that exhibits cut-resistant properties, yet may be used, for example, to form glove liners beneath surgical gloves. Such glove liners must afford a high degree of flexibility and allow a maximum of finger dexterity. Yet these glove liners must still exhibit a high degree of cut and puncture resistance.